Ambrose Evans-Pritchard has covered world politics and economics for 30 years, based in Europe, the US, and Latin America. He joined the Telegraph in 1991, serving as Washington correspondent and later Europe correspondent in Brussels. He is now International Business Editor in London. Subscribe to the City Briefing e-mail.

The Triumph of Parliament

What a momentous day for British democracy. The era of presidential rule is over. Parliament has reclaimed the powers chipped away by successive prime ministers, culminating with Tony Blair and the hegemony of spin. It has even snatched some powers it never had, beyond control of the purse.

There can be no going to war on executive authority alone, or by Royal Prerogative. Britain's living Constitution has been refashioned before our eyes, in seven hours of exhilarating debate. Much of the world's political class watched the debate unfold, riveted by the clash of moral argument. Has anything quite like it been seen since the Bulgarian Atrocities of 1876?

Whether David Cameron is down, or Ed Miliband is up, is essentially trivial. The Government handled the crisis badly, of course, no doubt pressured by Washington for premature action for reasons of military imperative. Assad is dispersing his targets. Every day counts. But this is the Schlieffen Plan reflex. You cannot let railway timetables dictate great power diplomacy.

It was foolish to even think of pre-empting the UN weapons inspectors, given what happened in the "poisoned well" of Iraq. They will determine exactly what chemicals were used. That is part of building a case. UN war crimes prosecutor Carla Del Ponte says the rebels are the only side known to have used Sarin gas. I have no idea whether or not she is right, but one might reasonably hesitate until we know a great deal more than we know now.

Many of us have been through this before. Personally, I was assured by (then Foreign Secretary) Jack Straw at a NATO summit in Brussels just before the invasion of Iraq that the Government had the intelligence on Saddam Hussein's WMD. "Just trust me, we have the proof but can't reveal sources," he said to four of us, all British journalists. We did indeed trust him, and bitter we are too, snake-bitten for ever.

Yet the reality remains that somebody killed over a thousand civilians in a Damascus suburb with chemical weapons, and the preponderance of evidence points one way. Will we let this precedent stand?

The Joint Intelligence Committee almost certainly "sexed down" the dossier this time, bending over backwards to be as banal as possible, but also because almost nobody in the upper echelons of the British security services and armed forces thinks that a fusillade of Tomahawk missiles makes much sense, if any. It is jejune to send "messages" in such a fashion. As one Labour MP put it, in warfare you are either "in or out".

I have been following this debate with a keen interest because my father – an Arab-speaker, then an Eighth Army Captain E. E. Evans-Pritchard – wrote the original intelligence report on the Alawite region of Syria in 1942 while planning for a post-War settlement. I am told that this included a classified profile of the Assad family, already seen as future leaders. There were very good reasons why the French and the British chose to rebuild Syria the way they did, searching for a formula that could hold together a mosaic of Orthodox Christians, Assyrian Chaldean Christians, Melkite Catholics, Alawites, Jews, Sunnis, Shiites, and Druze. Mess with that at your peril.

It is now said that Britain's `Special Relationship' with the US is in ruins. Such claims are melodrama. Much the same divisions exist internally within Congress, and within US public opinion. There will be a great many Americans who sympathise with the House of Commons, and who want their own restraining debate. Indeed, a hundred Congressmen have called for such a hearing.

President Barack Obama is rushing into half-baked action for the wrong reason, because he gave a hostage to fortune a year ago by declaring use of chemical weapons against civilians to be his red line. He is now preparing to go to war – for war it is – to uphold his own credibility. This is not a proper foundation for great power policy. Palmerston got away with it, but he chose his incidents more shrewdly. As former US National Security Advisor Zbigniew Brzezinski said this week, if Mr Obama has coherent policy on Syria "it is a well-kept secret".

We now have a colossal mess that can only end badly whatever happens. If the US acts it will stir up a hornets' nest without solving anything; and what happens if Assad survives the missile strike unscathed and then uses chemical weapons a second time?

Yet retreat at this late stage would be seen as abdication, risking a free-for-all across the region. I think that this is much exaggerated, and the lesser danger.

What Washington and London should have done is to build a moral and strategic case methodically, brick by brick. They should have exhausted the UN channels before uttering a single word about missiles, pushing first for a vote that placed Russia's Vladimir Putin on the record as the defender of chemical weapons atrocities. America should have used its diplomatic power to put China on the spot, forced to choose whether it wished to be in the same camp as the Pariah Putin, or one step safely removed.

Mr Obama should have held Russia's feet ever closer to the fire, refusing to attend the G20 in St Petersburg, flicking the "reset button" back off again, tightening a cordon sanitaire of Cold War isolation.

Let us not forget which is the superpower, and which is the basket case. For all the talk of American decline, the reality is that the US is storming back – soon to overtake Saudi Arabia as the world's biggest oil producer, and most likely to retain its economic dominance over China for at least another half century – while Russia faces demographic collapse, a victim of gross misgovernment, hobbled by the Resource Curse, left behind in the middle income trap. A few imbeciles may take Putin's bluster at face value, but no readers of this blog, I would hope.

The cynics will say that treating this crisis as a management task, conducted by calibrated diplomacy and soft power, will do more for Syrian civilians in the end than spasms of screen-fed emotion. Unfortunately, the cynics are often right.

My hope is that David Cameron will come out of this episode less damaged than assumed. His behaviour has been civilized, altruistic to a fault. He bent over backwards to secure consent. He gave Parliament the last say. There is no shame in honourable defeat, for an honourable cause.

I have reservations about Ed Miliband. The Labour Party was right to demand delay, but we are left with the deep suspicion that Mr Miliband played party politics, luring the Prime Minister into a snare. You do not do that in the Great Power league, or in the face of atrocities.

For Parliament, it has been a week of triumph. The House of Commons has prevented an historic blunder. It is asserting almost Cromwellian ascendancy, and will give up this power lightly to Europe's encroachments.

The will of the people has prevailed. Now we must deliver on our duty of care to the Syrian people as best we can.